Long-Covid less likely in breakthrough infections

This is really, I think, the first study showing that long-Covid is reduced by double vaccination, and it’s reduced significantly. Dr Claire Steves, lead author

People who experience breakthrough infections of the coronavirus after being fully vaccinated are about 50 per cent less likely to experience long-Covid-19 than are unvaccinated people who catch the virus, researchers said in a large new report on British adults.

The study, which was published in the journal Lancet Infectious Diseases yesterday, also provides more evidence that the two-dose PfizerBioNTech, Moderna and AstraZeneca vaccines offer powerful protection against symptomatic and severe disease.

“This is really, I think, the first study showing that long-Covid is reduced by double vaccination, and it’s reduced significantly,” said Dr Claire Steves, a geriatrician at King’s College London and the study’s lead author.

Although many people with Covid-19 recover within a few weeks, some experience long-term symptoms, which can be debilitating. This constellation of lingering aftereffects that have become known as long-Covid-19 may include fatigue, shortness of breath, brain fog, heart palpitations and other symptoms. But much about the condition remains mysterious.

“We don’t have a treatment yet for long-Covid,” Steves said, but getting vaccinated “is a prevention strategy that everybody can engage in”.

The findings add to a growing pile of research on so-called breakthrough infections among vaccinated people. The US Centres for Disease Control and Prevention has confirmed that the Delta variant is causing more of these breakthroughs than other versions of the virus, although infections in fully vaccinated people still tend to be mild.

The new findings were based on data from more than 1.2 million adults. The participants include those who received at least one dose of the Pfizer, Moderna or AstraZeneca vaccines between December 8 and July 4, as well as a control group of unvaccinated people.

Of the nearly 1 million people who were fully vaccinated, 0.2 per cent reported a breakthrough infection, the researchers found. Those who got breakthrough infections were roughly twice as likely to be asymptomatic as were those who were infected and unvaccinated. The odds of being hospitalised were 73 per cent lower in the breakthrough group than the infected, unvaccinated group. The odds of having long-term symptoms were also 49 per cent lower in the breakthrough group.

“Of course, vaccines also massively reduce your risk of getting infected in the first place,” Steves said. That lowered risk means that vaccination should reduce the odds of long-Covid by even more, she noted.

The study has limitations, the researchers acknowledge, the most notable of which is that the data is selfreported. Long-Covid is also difficult to study, with wide-ranging symptoms and severity.

But Steves said she hoped the findings might encourage more people to get vaccinated.